Solar furnace at Font-Romeu-Odeillo-Via, France. The concave mirrored surface on the wall of the nine-storey building reflects concentrated sunlight from heliostats on the ground (some just visible in the foreground) onto a furnace in the tower immediately in front. The resulting temperatures of up to 3,500 degrees Celsius are used to research the effects of high temperatures on various materials. The facility, which houses the PROMES laboratory, was designed by Felix Trombe and opened in 1970.